Apparatus for casting articles of metal



Apr.`17, 1923.

1,452,245 s. P. MARSHALL APPARATUS FOR CASTING ARTICLES OF METAL Filed oct. 22, 1921 2 sheets-sheet 1 Apr. 17, 1923.

s. f P. MARSHALL APPARATUS FOR CASTING ARTICLES 0F METAL Filed Oct 22 1921 2 Sheets-Sheet l 10 ings, forming a part thereof.4

15 valuablemetal for 'l .40 required mayv be perfectly Patented Api'. l?, I19253..

ED STATES PATENT OFFICE.

S'IANMIORF! PICKENS MARSHALL, OF CINCINNATI, OHIO, ASSIGNOR TO H. B. BYRD MANUFACTURING COMPANY, INCORPORATED,

OF WASHINGTON, DISTRICT F COLUMBIA, A CORPORATION OF VIRGINIA.

AIZPARATUS FOR CASTING ARTICLES 0F METAL.

`Application led October 22, 1921. Serial No. 509,593.

To all 'whom it may cof/wem.'

Be it known that I, STANMORE P. MAR- SHALL, a citizen of the United States, resid ing in the city of Cincinnati, county Aof Hamilton, and State of Ohio, have invented certain new and useful Improvements in Apparatusfor Casting AArticles of Metal, of which, the following is a specification, reference'being had to the 'accompanying draw- Myfinvention relates to an apparatus for casting metal particularly intended for dental castings, that is for the production of relatively Small castings of gold or other use as inlays for filling cavities, or as bridges or plates for supporting artificial teeth; In order -to cast inlays, bridges, plates or other'articles for use in dental 'work it is customary to make a pat- I tern by taking an impression inV wax of the be filled or to make' theppattern" cavity to from an impression of the portion of the mouth against which the bridge or plate is .f

to iit, and to form a mold or investment by packing investment material usually con-4 sisting mainly of plaster of Paris, about the wax pattern, 'rial to set and heating it to melt out` the wax pattern. Y

Much diiiicult'yhas been found in making perfect castings even under` pressure .-or.

vacuum for the reason that (if the mold is cold, the molten metal will .chill to such an p extent as not' to reach the more delicate parts o'f the mold and, ifthe mold is heated suiii ciently to avoid chilling, the mold and the casting is distorted. It is the object of my invention to provide `an apparatus by which the delicate castings formed in a cold mold, thus avoiding any chilling before the molten metal reaches everyp'art of the mold and also avoidingl the distortion resultingy from casting, in a hot mold.

A further-object of my invention is to provide al compact and simple apparatus adapted for carrying out my method which Y will not readily get out of'order and will be adapted for general use and will not require s ecial skill. A further object oftheinvention is to provide an apparatus in which the operation of casting,after the-metal'has been melted, may be effected by the operationV of a single lever, A further -object of -vention allowing the investment mate- A of any convenient the full force of the air pressure and vacu-v um used is caused to act directly on the molten metal to force it into the mold. A further object of the invention is to provide a method and apparatus by which a mold having a single relatively large sprue hole may' be used.

With the objects above set forth and other objects hereinafter explained, in view my indescribed and claimed.

Referring to .the drawings:

Figure 1L is a side view of a complete dental casting apparatus embodying my invention looking toward the right'.

Fig. 2 is av vertical centralcsectional view of the iash, melting crucible and connected parts. f Fig. 3 is a detail view partly in section of the pipe connecting the pump with the pres- '.sur'e and vacuum chambers of the tank.

- Fig. 4 is a side view similar to' Figure 1 but taken from the opposite side and lshowing the device without the fiask, and

Figs. 5 and 6 are detail views showing the casting crucible in closed and open position. In the drawings 1 indicates `a ask in which'the mold is held. This flask is here v'shown as cylindrical metal box but may bc shape and is provided 2 and a lower neck 3, the

with an upper neck faced olf so'that the end ends of which are -of the upper neck is adaptedt fit tightly against a seat 4 in the bottom of an enclosing receptacle in which'is arranged the melting crucible 6, and the end of the` lower neck is adapted to fit tightly against a seat 7 on the upper endA of an adjustable support 8 having a central passage 9 formed .f through 1t.

Within this fiask is formed the imold 10 having a single sprue hole 11 of relatively large diameter leading to it from a point in line with the axial center of the upper neck 2.

Thel mold is formed in the usual way by en` closing a pattern consisting of a wax impression of the inlay, bridge, plate or other article to be cast, in a suitable investment comconsists in the apparatus hereinafter of both vacuum and pressure In the upper neck 2 is arranged a funnel i 12 with the opening 13 at its lower end in line with the upper end of the sprue 11. A

lining 14 of sheet asbestos is usualy arranged in this Crucible to protect the molten metal from contact with the metal of the funnel 12 and consequent chilling, as it passes into the mold. The funnel is supported in the neck 2 in any convenient manner. In the construction shown the funnel is provided at its upper edge with an annular flange which rests on the upper end of the -neck 2 and is clampedbetween it and the seat 4.

- The receptacle 5 has an opening 15 in its bottom in line with the opening in the upper neck 2 and around this opening, at its lower end, the seat 4 is formed. In the receptacle 5 and above and concentric with the opening 15 is arranged the` melting Crucible, which is formed in two halves 16 and 17, which come together in a vertical plane. These halves 16 and 17 are carried respectively by the forwardly extending arms of bell` crank levers 18 and 19-carried by fixed pivots 20 and 2l and having inwardly extending arms 22 and 23 respectively which are engaged by oppositely arranged notches 24 and 25 in a cross head 26 which is arranged to be reciprocated by mechanism hereinafter described.

The receptacle 5 is provided with a removable cover 27 which, by mechanism hereinafter described, is clamped down upon it.

Into the receptacle 5 leads a pipe 28 which is in communication with a supply of compressed air and the central jpassage 9 of the adjustable support 8 is in communication with means for exhausting the air from the mold through it.

30 indicates a base plate on which is supported, at the rear, a tank 31 divided by a partition 32 into an upper pressure chamber 33 and a lower vacuum chamber 34. A secondary base plate 35 forward of the tank supports the mold and the operating mechanism.' From this secondary base plate 35 ay vertical post 36 extends upward near the tank. An upper plate 37 supported on the post 36 and forward legs 38 carries the receptacle 5. From the forward end of this upper plate 37 brace rods 40 extend to the upper end of the vertical post 36 forming a rigid structure.

A pump barrel 42 'is connected at its rear end with a vertical pipe 43, the upper end of which leads into the pressure chamber 33 and the lower end of which leads into the vVacuum chamber 34. Between the point at which the pump Ybarrel 'this vertical pipe and its upper end is a is connected with hand valve 44 and an upwardly opening check valve 45 and between the point at which the pump barrel is connected with this vertical )pipe andits lower end is a hand valve 46 and a check valve 47. The pum-p rod 48 is provided on its end with a piston 49 arranged for both pressure and exhaust.-

The tank ,is provided with gauges 50 and 51 of which gauge 50 is in communication with the pressure chamber 33 and gauge 51 is in communication by pipe 53 with vacuum chamber 34.

On reciprocating the pump rod, the hand i valves 44 and 46 being open, air will be forced into the pressure chamber and withdrawn from the vacuum chamber. When the gauges show the required pressure and vacuum the hand valves should be closed.

From the vacuum chamber 34 a pipe 60 leads to a valve 61 from which a pipe 62 leads to a vertical pipe 63 into the upper end of which'the adjustable support 8 extends. A nut 64 turning on thev upper end of pipe 63 and engaging the screw thread of the adjustable support serves to force it upward. n

From the pressure chamber' 33 a pipe 70 leads to a valve 71 from which pipe 7 2 leads to pipe 28 which is in communication with the interior of the receptacle 5.

The valves 61 and 71 are self closing valves of any ordinary type, such as the ordinary steam whistle valve, and are arranged to be opened by pushing forward the valve rods and 75.

The cross head 26 for operating the bell crank levers 18 and 19 is carried by a rearwardly extending rod 85. These valve'rods 65 and 75 and the rod 85 are parallel and in the same vertical plane. The levers 66, 76 and 86 for operating these rods are pivoted respectively in supports 67, 77 and 87 and their lower ends 68, 78 and 88 bear against the rear ends ofthe respective rods in position to be operated by cams 60, 79 and 89 carried by a vertically sliding rod 90.

The cover. 27 for the receptacle 5 is provided on its upper face with a boss in f which is pivoted the forward end of an arm 101 the V,rear'end of which is pivoted in the forward end of a fixed arm 102 carried by and extending forward from the post 36. Also pivoted to the boss 100 of the cover 27 is the lower end of the lower member 103 of an elbow lever, the upper member 104 of which is pivoted 'at 105 to a bracket 106 carried at the upper end of post 36. 0n the pivot 105 is secured the end of operating lever 107 provided with handle 108. being so arranged that swinging this lever will swinothe upper member 104 with it. The members 103 and 104 of the elbow member are so constructed that when the operating lever is swung down into the position shown lim be in a straight line and will hold the cover 27 firmly onto the receptacle 5.

Also pivoted in the forward end of fixed arm 102 is a'bell crank lever having its horizontal arm 110 extending rearward and engaging a notch 111 in theupper end of the vertically sliding rod v90, and having its vertical arm 112 in position to be struck and forced rearward by the upper member 104 of the elbow lever as it nears the limit of its downward swing, the movement thus 'iin-- them to push forward the valve rods and` and the rod 85 to open valves 61 and 71 and to operate thexbell crank levers 18 and 19 to separate the halves"16 and 17 of the melting Crucible.

The cam 69 is made slightly longer than the cams 79 and 89 so as to effect the operation of valve 61 slightly before the valve 71 and the rod are operated.

A spring 115 on the vertically sliding rod serves to restore it to initial position when the operating lever 107 is raised.

ln making use' of this apparatus the flask 1 having the mold in it is secured in place with its upperV neck against the seat 4 and its lower neck resting on seat 7, the nut 6l being rotated to raise support 8 until tight joints are formed between the necks and their respective seats, as well as a tight joint between the funnel 12 and the seat e and neck 2. rll`he pump rod 48 is then operated to produce the proper pressure in the pressure chamber and the proper vacuum in the vacuum chamber. Gold or other metal to be used is thenfrnelted in the crucible 6, usu4 ally by a blow pipe. When itis sufficiently liquid 'the lever 107 is brought down to bring the cover 27 down onto the receptacle 5. As the cover is about to make close contact with the top of vreceptacle 5, the upper member 104 of the elbow leveracts on the arm 112 of the bell crank lever to force vertically sliding rod 90 downward against the force of spring 115. As the rod 90 begins to 'move downward it carries cam 69 against the lever through which valve 61 is opened,

y thus connecting the flask witlr the vacuum chamber and exhausting the airfrom the mold. Almost instantly thereafter the cams 89 and 79 act to effect the separationof the halves of the melting erucible` dropping the molten metal into the funnel 12, and also opening valve 71 to permit air under pressure to enter thereceptacle 5 and act downward on the molten metal which has dropped or is dropping into the funnel 12. By thus forcing the molten metal into the lmold previously exhausted of air. it is driven mto the mold with such rapidity that it -flows into the most delicate parts of the mold before it is sufficiently chilled to be sluggish. While of course the operator needs to be skilled in melting the gold or other metal used, and must see to it that the proper pressure and vacuum is shown by the gauges and that the nut 64 is turned sufficiently to insure tight joints at the ends of the necks or the flask, no special skill is required as, when the metal is melted, all that remains to be done is to brin down the lever '107 until it can be forced own no further.

It is of course to be understood that the lflask l is substantially air-tight except at the openings formed by the necks 2 and 3, so that whenthe valve 61 is opened the suction ofthe vacuum chamber will exhaust the air from theI mold, there being no place i at which air can enter the flask except through the small opening 13 at the lower end of the funnel 12, and this opening is filled by the molten metal as it is discharged from the Crucible, rll`he molten metal is then between the suction of the vacuum chamber and, the receptacle 5 being closed and the valve 71 being opened, the pressure from the pressure chamber, and is thus both drawn into and forced into the mold.

Y The parts of the Crucible 6 when brought together should fttogether sufficiently close-l ly to prevent any of the molten metal from dropping through into the funnel 12 and the sprue hole 11 before these parts are separated topermit the mass to drop. rfher'e is thus no danger of the sprue hole becoming choked byy metal before the casting operation, as is liable to happen when' the metal is melted directly on the mold, as is usually done in dental casting. By reason of th'e fact that the molten metal, in carrying out my invention as above described, is dis'- charged in a single mass at one time into the funnel 12 and through it into the sprue hole 11 and is instantly forced into the sprue hole by the suction below the mold and the air `pressure above the metal, the metal entering the single sprue hole will be distributed to all parts of a mold cavity even of such extensive area as that for casting a plate. The necessity for a plurality of sprue holes heretofore found necessary in casting a plate or other article of extensive area and the necessity for the metal flowing in through the separate sprue holes to unite. in the cavity ofthe mold is avoided. lt has heretofore been found practically impossible to cause the metal entering the mold through separate sprue holes to unite I satisfactorily in the cavity of a cold mold and very difficult to secure satisfactory unf roe '- holes covers only the central portion of the depression formed to receive it. Consequently when the air is exhausted from the mold more or less air will be drawn in through the portion of its top surrounding. the molten metal, the mold being of porous material. This necessarily reduces the effective pressure on the molten metal so that the pressure gauge does not correctly indicate the effective pressure and there is thus no way of' determining what the effective pressure really is. In the use of my invention this uncertainty is avoided as there is no opportunity for leakage of air about the molten metal, the top of the mold being protected by the funnel 12 with its tight connection withthe neck 2 and seat 4. The operator can thus be sure that the pressure indicatedv by the pressure gauge is the effective pressure upon the molten metal.

The mold being formed of the usual investment material used in forming molds for dental casting is somewhat porous,'suf ficiently so as to permit the air to be exhausted through it. It may be formed of any material of a similar porous nature, and the exhausting of the air from it may be facilitated in any usual way as by forming vent holes in it leading from the lower opening of' the flask; such vent holes, however, preferably not extending to the cavity of the mold.

While theapparatus is particularly adapted for dentists use in making the relatively small casting used in dental work, I do not desire to be understood that the invention is limited to making castings of any particular size or of any particular metal.

Having thus described my invention what I claim is:

1. In an apparatus for casting articles of metal the combination with a flask adapted to enclose a mold of porous material and having an upper `and a lower opening, of a receptacle above the upper opening of the flask and in communication therewith, a crucible within the receptacle above the upper opening ef thellask and at such dlstance from it as to leave a substantial air space between the crucible and the fla-sk, means for creating a partial vacuum within the flask, and means for discharging the contents of the crucible into the upper opening of the flask. 2

2. In an apparatus for casting articles of metal the combination with adflask adapted to enclose a mold of porous material and having an upper and a lower opening, of a normally open receptacle above the upper opening of the flask and in communication therewith, a crucible within the receptacle abovethe upper opening of the flask and at such distance from it as to leave a substantial air space between the crucible and the flask, means for creating a partial vacu- 3. In an apparatus for casting articles of metal the combination with a flask adapted to enclose a mold of porous material and lhaving an Lipper and a lower opening, of

a receptacle above the upper opening of the flask and in communication therewith, a crucible within the receptacle above lthe upper opening of the flask and at s uch distance from it\as to leave a substantial air space between the crucible and the flask, means for creating a partial vacuum in the flask. means for discharging the contents of the crucible into the upper opening of the flask, and means carried by the flask for guiding the contents of the crucible into the sprue hole of the mold enclosed therein.

4. In'` an apparatus for casting articles of met-al the combination with a. flask adapted to enclose a mold of porous material and having an upper and a lower opening, of a ,receptacle above the upper opening of the flask and in communication therewith, a crucible within the receptacle above the upper opening of the flask and at such distance from it as to leave a substantial air space between the crucible and the flask, means for creating a partial vacuum in the flask, means for discharging the contents of the crucible into the upper opening of the flask and a funnel carried by the flask for guiding the contentsof the crucible into the sprue hole of the mold enclosed therein.

5. In an apparatus for casting articles of metal the combination with a flask adapted to enclose a mold of porous material and having an upper opening and a lower opening, of a receptacle above the upper opening of the flask and in communication therewith, a crucible within the receptacle above the upper opening of the flask and at A'such dista-nce therefrom as to leave a substantial air space between it and the flask, means for holding the upper opening of the flask tightly against the bottom of" the receptacle, air exhausting means adapted to be placed in communication with the lower opening of the flask, and means for dischargingthe contents of the crucible into the upper opening of the flask, and means for connecting the exhausting means with the flask to crea-te a partial vacuum therein and then discharging the contents of' the crucible.

6. In an apparat-us for casting articles of metal the combination with a ask adapted to enclose a mold of porous materiall ,and having an upper opening and a lower opening, of a normally open receptacle above the upper opening of' the flask and in communiing,

cation therewith, a.crucible within thel receptacle above the upper opening of the flask and at such distance therefrom` as to leave a substantial air space between it and the flask, means for holding the upper opening of the flask tightly against the bottom of' the' receptacle, air exhausting. means adapted to be' placed n communication with the lower `openingof the flask, means for closingfthe receptacle,V air pressure means adapted tobe placed in ACommunication with the receptacle, and means for discharging the contents' of the crucible into the upper opening of the flask.

7. In-'an apparatus for metal the combination with a flask adapted to enclose a mold of porous material andv having an upper opening and a lower openof a normally open receptacle above the upper opening of' the flask and in communication therewith, aA Crucible within the receptacle above the upper opening of the fiask and at such distance therefrom as to leave a substantial air space between it and the flask, means for holding the upper opening of the flask tightly against the bottom of the receptacle, .air exhausting meansadapted 'to be placed in communication with the lower opening of the flask, means for closing the receptacle, air pressure means adapted to be placed in communication with the receptacle, and means for discharging the contents of the Crucible into the upper opening of the flask, and means for first connecting the exhausting means with the flask to create a .partial vacuum thereinand thensimultaneously Closing the receptacle, discharging the contents of the Crucible and turning on the air pressure.

8. In an apparatus for casting articles of metal' the Combination with a vflask adapted to enclose a mold of porous material and having an upper opening and a lower opening, of a normally open receptacle above the upper opening of the flask and in communilcation therewith, a Crucible withinthe receptacle above the upper opening of the flask and at such-distance` therefrom as to` leave a substantial air space between it and the flask, means for holding the upper opening of the flask tightly against the bottom Casting articlesv of of the receptacle, air exhausting vmeans adapted to be placed in communication with the lower opening of the flask, means for closing the receptacle, air pressure` means adapted to be placedl in communication with the receptacle, and means for discharging the contents ofthe Crucible into the upper openingqof' the flask, an operating handle and means operated thereby for first connecting the exhausting means with the flask to create a partial vacuum therein-and then simultaneously closing the receptacle, discharging the contents of the Crucible and turning o n the air pressure.

9. In an apparatus for casting articles of metal the combination with a flask adapted to enclose a mol of porous material and having anupper opening. and a lower opening, of a normally open receptacle above the upper openingotl the flask and in communication therewith, and having a removable cover, a Crucible within .the receptacle above the upper opening of the flask and at such flask, andmeans for first Jconnecting the exhausting means with the flask tot create a partial vacuum therein and then simultaneously closing the receptacle, discharging the contents of the Crucible and turning on the air pressure, to force the Cover onto the receptacle and a vertically movable rod carrying cams for operating the valves of the air exhausting and air pressure means and for operating the v'means for discharging the contents of the crucible. 1

In testimony whereof I hereunto affix my signature.

i STANMORE PICKENS MARSHALL.

comprising a lever arranged- 6 Certiicate of Correction.

f I Itis hereby certifiedlthat Letters Patent No. 1,452,245, ranted April 17, 1923, upon the application of Staninore Pickens Marshalhof Cincinnati, Ohio, for an improvement in Apparatus for Castin Articles of Metal, were erroneously issued to H. B. Byrd MfiniifaturingX ,-onipginy, Incorporated, of Vashington,v

District of Columbia, a Corporation of v7irginiai, :is assignee of the entire interest in said invention, Whereas said ILet-ters'Patent should have issued to the inventor, said Marshall, and' H. I?. Bgm? Manufacturing Company, Incorporated, said `corporat1on being assignee of one-kalf interest only in said invention, as shownby the records of assignments in this ofice; and that the said Letters Patent record of the casein the Patent Olice.

Signed and sealed this 29th day of May, A. D., 1923. f l [SEAL] 'L l KARL FENNING,-

Acting 0mm/mnner of Patents. 

